One of my friends recently stated: "black is not a colour. It is the entire absence of it, both physically and neurochemically." But can this be right? I understand what my friend is saying in that things appear black when they don't emit or reflect any photons of light, and that, as a result, there is nothing for the light sensitive cells in our eyes to detect. However, in everyday life we still view black as a colour, just as we do red or green.
I should probably mention that my friend is a scientist and tends to take a strictly empirical and sometimes rather reductionist view of things. Consequently, I'm keen to get a broader perspective on this question from a philosopher.
So, my question then is: is black a colour? Or, perhaps more accurately, does it even make sense for us not to consider black a colour?

Comments

This is a great, deep question that others will be far more qualified than I to answer appropriately. But one might perhaps start by simply recognizing a fundamental ambiguity in the notion (or meaning of the word) "color." Sometimes by that notion we imply something we take to be physical in nature, a physical property, or a property of physical bodies (or perhaps of light itself), something objective; on that view arguably black would not be a color (if indeed blackness is the absence of all light, so there would be nothing there to have that color). (I actually think that in the complete absence of light human beings see a kind of gray rather than black, but never mind.) But sometimes by "color" we mean something 'mental,' something subjective, something perceived, and here we would likely take black to be as genuine a color as any other, since we can perceive it. Of course it turns out that color conversations quickly get a lot more complicated, because it is not at all straightforward to identity even ordinary perceived colors (red, orange, yellow ROYGBIV) with physical properties, but at least recognizing this ambiguity in the basic notion of color will get you started on reframing your question a bit: what is the exact relationship between colors as perceived and the physical properties of the world?

Here is an answer I gave on February 10 2010. For your reductionist friend I would answer that the perception of black is positive - it is not a null perception, in some sense, but nor is it the perception of nothing, so that nothing (or Nothing, rather) looks black - presumably It doesn't look any colour. I also want to add that black is not in the spectrum, obviously, for what that is worth (nothing, actually) and that "black" and "dark" have different meanings. If you take a dimmer switch and gradually increase the light in a completely dark room, as the illumination goes up, the reds get redder, the greens greener, and amzaingly the blacks get blacker! What does this tell us?

From Feb 10 2012 This is a fairly frequent concern. The correct answer is that there is a sense of "colours" in which black and white are not colours (they are not chromatic colours) and a sense in which they are colours (they are achromatic colours). So if we count the achromatic colours (black, white and grey) as colours, then black and white are colours. (Brown is an interesting case, as it is a colour which is partially achromatic.) In the same way, we can ask whether zero and infinity are numbers. Usually they are treated as numbers, and they have their own mathematical symbols. We can manipulate them in calculations and so forth. But in another sense "zero" denotes the absence of a number, and so does the symbol for an infinite number. Q: "How many chickens were there in the kitchen?" A: "A number." Q: "What is the number?" A: "Zero"! Aristotle's view was that the smallest number is two, as one of something is not a number of somethings. "There were a number of people there." How many?" "One." In this sense two is the first crowd-like or milling number. One won't mill around. Logicians face the same difficulty in explaining that in their sense "some" means only "at least one".

The situation is that colours arrange themselves into three dimensions: saturation, hue, and brightness. Hue is colourfulness, the colourfulness of red, yellow, blue, green and so on, and colourfulness does not include black, white and grey. Colourfulness is the circling hue dimension at maximum saturation, and the achromatic colours lie in their own vertical dimension at the center of the solid whose surface is this colourfulness or saturation. White has zero saturation, and we make other pigments of various chromatic colours less saturated - paler - by mixing in white pigment. (It is an interesting question why this concept - paleness - has a "special relationship" only with white.)

So at the end of the day the fact is that in one way black and white behave as colours, and in another way they work to create diminutions and absences of colour. Wittgenstein was right (in his Remarks on Colour) to see a puzzling element of necessity, a necessity as hard as logical necessity, in these striking facts.